Coil wire fastening device and method



June 30, 1970 E. A. coNNELl. 3,518,596

COIL WIRE FASTENING DEVICE AND METHOD "United States Patent llice 3 518 596 conJ WIRE FASTENIG DEVICE AND METHOD Edwin A. Connell, Hendersonville, N C., assignor to general Electric Company, a corporation of New ork Filed July 29, 1968, Ser. No. 748,325 Int. Cl. H01f 15/.10

U.S. Cl. 336-192 10 Claims ABSTRACT OF THE DISCLOSURE Toroidal coil is provided with annular insulating washer having slit tabs under each of which a wire turn is inserted and over which adjacent wire turns are wound for securing the ends of the coil winding.

The present invention relates to electrical coils, and more particularly to a fastener device for securing the ends of coil windings.

It is an object of the invention to provide an improved fastener device for securing the wire windings of an electrical coil.

It is a particular object of the invention to provide a simple and economical device for fastening the ends of the wire windings on toroidal electrical coils.

It is. another object of the invention to provide an improved method of winding and fastening the turns of a wire coil using a fastener device of the above type.

Other objects and advantages will become apparent from the following description and the appended claims.

With the above objects in view, the present invention relates in a preferred embodiment to an electrical coil which comprises a tubular member, an annular insulating member overlying the end face of the tubular member and being formed with circumferentially spaced tabs therein, and a wire coil wound on the tubular member between the spaced tab portions, the wire turn at each end of the coil passing under the respective tabs and the adjacent wire turns being wound over the respective tabs, whereby the coil winding is securely anchored to the tubular member.

The invention will be better understood from the following description taken in conjunction with the accompanying drawing, in which:

FIG. 1 is a perspective view of a toroidal electrical coil embodying the present invention;

FIG. 2 is a top plan view of the coil fastening device of the invention;

FIG. 3 is a fragmentary perspective view of one of the fastening tabs and associated starting wire turns of the coil shown in FIG. 1; and

FIG. 4 is a fragmentary plan view of another of the fastening tabs and associated nish wire turns of the FIG. 1 coil.

Referring now to the drawing, and particularly to FIG. 1, there is shown a transformer of a type adapted for use with airport runway lighting equipment and cornprising a tubular base 1 formed of electrically insulating material such as rubber in which is encased a cylindrical magnetizable metal core (not shown), with a primary winding 2 and a secondary winding 3 wound on the tubular base 1 in toroidal form as shown. Annular insulating members or washers 4 and 5, such as of ber board, pressboard or the like, are arranged at opposite end faces of tubular base or core 1 and underlie the turns of the coil windings of the wire, which typically has a conventional coating of insulating varnish or the like. In accordance with the invention, at least the upper insulating washer 4 (see FIG. 2) is provided with pairs of circumferentially spaced tab portions 4a, 4b, 4c, 4d which are slit from the body of the washer and by means of 3,518,596 Patented June 30, 1970 which the end turns of the respective windings are securely fastened for retaining the coil in tightly wound condition. Each tab is so slit from the washer as to have a main tongue-like portion integrally attached at one end to the washer and about which the tab is readily bendable. The tabs in each pair are, as shown, cut so that their free ends are directed toward each other.

In' winding coil 2, tabs 4a, 4b are initially bent up at right angles to the surface of the washer, the starting endZ'a of the wire (see FIG. 3) is placed on washer 4 close to the base or attached end of tab 4a, the tab is then bent down ilat over the wire, and the adjacent turns of the wire are wound over the top of the main portion of the tab, so that end wire portion 2a is snugly held between the bottom of tab 4a and the adjacent portions of washer 4. Prior to reaching tab 4b in the course of winding coil 2, the latter tab is bent d own over a suitable pinfor the like having a slightly larger diameter than the wire and placed against the washer surface, the finish turns of the wire are then wound over the top of tab 4b, the ,pin is removed and the finish end 2b of the wire coil is inserted through the loop thereby formed between the tab and the washer. Both the start and the finish ends of the coil are bent at right angles where they emerge from under the tabs, thereby preventing the wound wire from becoming loosened.

In a preferred embodiment adapted for use in transformers of the type illustrated, those portions 4e, 4f of the washer between the perforations 6 shown in FIG. 2 may advantageously be torn out after the coil windings havebeen formed so as to leave the underlying end portions of tubular base 1 exposed and thereby facilitate adhesion thereto of an encapsulating material usually applied over the final core and coil assembly in accordance with known practice.

As will be understood, the tab portions, if any, of the washer on the bottom end of core l are not employed for fastening purposes and would be left entirely ilat in the washer as the coil is wound thereon without being inserted under the tabs.

There is thus provided by the invention, a simple and inexpensive means and method for winding and fastening wiret coils such as induction coils or the like, which firmly anchors the coil ends and holds the coil in secure assembly on the core member.

While the present invention has been described with reference to particular embodiments thereof, it will be understood that numerous modifications may be made by those skilled in the art without actually departing from the scope of the invention. Therefore, the appended claims are intended to cover all such equivalent variations as come within the true spirit and scope of the invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. An electrical coil comprising, in combination, a tubular core member, an insulating sheet overlying an annular end face of said core member and formed with a circumferentially extending elongated tab having an attached end and a free main portion bendable about its attached end toward and away from the plane of said sheet, and a wire coil wound in toroidal form over said core member and said insulating sheet, an end portion of said wire winding lying beneath said tab at its attached end and adjacent turns of said winding being wound on top of said main tab portion transversely thereof for retaining the same substantially in the plane of said insulating sheet, whereby said wire end portion and said coil are securely fastened to said core member and said overlying insulating sheet.

2. A device as defined in claim 1, the end portion of said wire winding emerging from beneath said tab being 3 bent substantially at right angles to the plane of the tab to prevent loosening of said winding.

3. A device as defined in claim 1, said insulating sheet having a second tab similar to and spaced from said firstmentioned tab with said tabs directed toward each other, the opposite wire end portion and wire turns adjacent thereto being arranged relative to said second tab as said corresponding parts of the coil at the first-mentioned end are arranged relative to said first-mentioned tab.

4. A device as defined in claim 3, both said end portions of said wire winding emerging from beneath the respective tabs being bent at right angles to the plane of the tabs to prevent loosening of said winding.

5. A device as defined in claim 4, said insulating sheet being substantially coextensive with said annular end face of said core member and having a second pair of tabs similar to said first-mentioned tabs, and a second coil winding on said core member arranged and fastened thereon similarly to said first-mentioned coil winding.

6.. A device as defined in claim 5, said insulating sheet being formed in regions between said pairs of tabs with attenuated portions for removal of portions of said sheet in said regions.

7. In the method of winding a toroidal electrical coil on a tubular core member, the steps of providing on an annular end face of said core member an insulating sheet formed with a circumferentially extending elongated tab having an attached end and a free main portion, inserting beneath the attached end of said tab the starting end of the wire to be wound, and winding the adjacent turns of the wire coil on top of the main portion of said tab transversely thereof while winding the wire in toroidal coil form on said core member for retaining said tab substantially in the plane of said insulating sheetand securing the starting wire end portion under said tab.

8. The method as' defined in claim 7, said insulating sheet having a second tab similar to, spaced from, and directed toward the first-mentioned tab, Winding the iinish turns on top of the main portion of said second tab transversely thereof for retaining the same substantially in the plane of said sheet while providing an opening under the attached end of said second tab, and inserting the finish end portion of the wire coil through said opening.

9. The method as dened in claim 8, and bending the start and nish wire portions emerging from beneath the respective tabs at right angles to the plane of the tabs for preventing loosening of the wire coil.

10. A method as defined in claim 8, said insulating sheet being substantially coextensive with said annular end face of said core member and formed with a second pair of spaced tabs similar to said first-mentioned pair of tabs, the method including winding and fastening a second toroidal coil on and between said second pair of tabs, and removing portions of said insulating sheet member between said coils for exposing the underlying end face of said core member.

References Cited UNITED STATES PATENTS 1,919,019 7/1963 Greenidge 336-196 X 2,779,928 1/1957 Jeffrey 336-196 FOREIGN PATENTS 664,325 8/ 1938 Germany.

ELLIOT A. GOLDBERG, Primary Examiner U.S. Cl. X.R. 

